Re: [igraph] Problem with C attribute handler

From:

Gábor Csárdi

Subject:

Re: [igraph] Problem with C attribute handler

Date:

Thu, 17 Sep 2009 14:46:56 +0200

On Tue, Sep 15, 2009 at 1:05 AM, Juanjo Jimenez <address@hidden> wrote:
> We compiled your code and it works fine. But we are not sure that this would
> solve our problem. We tested your code replacing your modification with our
> original function. It works fine too. Beyond the fact that we should have
> done something like you did to skip the line, we believe that our problem is
> somewhere else.
No, your code is wrong. You are lucky that it works, but that is just
by chance. With a different compiler or platform it will not work, the
errors are random and unpredictable. For me it gives 'segmentation
fault'.
[...]
> - The implementation of the R interface assume that if you want to access to
> the attributes, you would do it from R and not at a lower level, hence, the
> implementation does not support what we intended.
[...]
Well, kind of. You can query the attributes from C, using the
igraph_i_attribute_* functions (see igraph_attribute.h). But cannot
mix attribute handlers, because they store the attributes in different
data types. E.g. the R attribute handler can store R objects, this
does not make sense in C.
Best,
Gabor
--
Gabor Csardi <address@hidden> UNIL DGM